Engineering group Amec is topping the FTSE 100 risers following news it had withdrawn from the bidding for oil and gas specialist Kentz.

Amec had an approach worth between 565p and 580p a share rejected by Kentz last month, and had until 16 September to decide whether to proceed. In the event it has decided there are better options elsewhere. It said it had a strong pipeline of opportunities, and would also consider returning cash to shareholders in the fourth quarter, depending on the progress of any acquisitions. All that helped send Amec's shares 27p higher to £10.85.

German group M+W had also approached Kentz, but had so far made no further approaches. The 16 September deadline still applies in this case.

Kentz shares have dropped more than 10% to 490.1p, and Arden analyst Daniel Slater said:

Of the two bidders Amec was always the more likely acquirer of Kentz given its existing oil and gas industry presence and now that the company has walked away it makes a deal look unlikely in our view not least given that no other bidders for the company have appeared other than M+W.

While the bid interest looks like coming to nothing this time it does lend industry endorsement to our long held view that Kentz has been undervalued by the market.

Meanwhile the FTSE 100 has lost its earlier, rather tentative, gains and is now down 20.32 points at 6568.11. Poor industrial production figures from Europe have taken the shine off things, while investors still remain uneasy about Syria, especially with the odd rumour of rockets being fired in the region.

Ahead of next week's US Federal Reserve meeting there is also concern the central bank may start turning off the money taps, the process which has been supporting the markets for some time.

Elsewhere Aggreko is leading the FTSE fallers, down 55p at £15.96 as Deutsche Bank cut its price target but kept its buy rating. The bank said:

Contracts in power projects have been hard to come by over the past 12 months but we are still of the view that the lack of contract conversion is an issue of timing rather than anything structural. Although we have no precise visibility on the timing of contracts being signed, we think it is right to take a cautious stance given emerging market GDP and foreign exchange weakness. We therefore move to a scenario whereby underlying pretax profit is broadly flat in 2014 versus 2013, implying an 11.6% cut to our 2014E earnings per share which now sits at 83.3p. Our target price falls to 1870p from 2100p, but we retain our buy recommendation as we expect better contract conversion in 2014.